This invention is directed to a structural assembly designed to absorb impact so as to minimize the threat of radially bending the crankshaft of a gas engine--in this instance, an engine in a rotary lawn mower.
Briefly, the protection is provided by building into the structure (i) a stiffener assembly which functions to absorb impact energy while minimizing radial deflection of the crankshaft and (ii) a friction slip clutch type of mounting to permit the cutting blade to rotate relative to its fastener.
Though the engine crankshaft is generally used to rotate the cutting blade directly, the invention will apply to any exposed shaft.